<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>用纯CSS创建一个三角形的原理</title>
</head>
<style>
    a {
        text-decoration: none;
    }

    a:link {
        color: blueviolet;
    }

    a:visited {
        color: aquamarine;
    }

    a:hover {
        color: wheat;
    }

    a:active {
        color: yellowgreen;
        
    }


    div {
        width: 0;
        height: 0;
        border-top: 40px solid transparent;
        border-left: 40px solid transparent;
        border-right: 40px solid transparent;
        border-bottom: 40px solid #ff0000;
    }
</style>

<body>
    <div></div>
    <a href="">a链接</a>
</body>

</html>